The present invention relates to fabric conditioning compositions. More specifically, the invention relates to stable fabric-softening compositions comprising an ester-linked quaternary ammonium compound, an emulsified silicone and a long chain fatty compound.
It is well known to provide liquid fabric conditioning compositions, which soften in the rinse cycle.
Such compositions comprise less than 7.5% by weight of softening active, in which case the composition is defined as xe2x80x9cdilutexe2x80x9d, from 7.5% to about 30% by weight of active in which case the compositions are defined as xe2x80x9cconcentratedxe2x80x9d or more than about 30% by weight of active, in which case the composition is defined as xe2x80x9csuper-concentratedxe2x80x9d.
Concentrated and super-concentrated compositions are desirable since these require less packaging and are therefore environmentally more compatible than dilute or semi-dilute compositions.
A problem frequently associated with concentrated and superconcentrated compositions, as defined above, is that the product is not stable upon storage, especially when stored at high temperatures. Instability can manifest itself as a thickening of the product upon storage, even to the point that the product is no longer pourable.
The problem of thickening upon storage is particularly apparent in concentrated and superconcentrated fabric softening compositions comprising an ester-linked quaternary ammonium fabric softening material having one or more fully saturated alkyl chains.
However, it is desirable to use ester-linked compounds due to their inherent biodegradability and to use substantially fully saturated quaternary ammonium fabric softening compounds due to their excellent softening capabilities and because they are more stable to oxidative degradation (which can lead to malodour generation) than partially saturated or fully unsaturated quaternary ammonium softening compounds.
Of the types of ester-linked quaternary ammonium materials known, it is desirable to use those based on triethanolamine which produce at least some mono-ester linked component and at least some tri-ester linked component since the raw material has a low melting temperature which enables the manufacturing process of the composition to occur at low temperatures. This reduces difficulties associated with high temperature handling, transport and processing of the raw material and compositions produced therefrom.
Frequently, it is desirable to add further ingredients into fabric conditioning compositions in order to provide additional benefits.
One such additional ingredient is an emulsified silicone. Emulsified silicones are desirable because they can provide fabric-conditioning compositions with anti-crease and ease of ironing benefits.
WO-A1-00/71806 discloses a fabric softening composition comprising a cationic fabric softening agent; and an emulsified silicone; wherein the viscosity of the silicone before emulsification is from 10,000 cSt to 1,000,000 cSt, preferably from 30,000 cSt to 750,000 cSt, more preferably from 40,000 cSt to 300,000 cSt and the emulsion is a macro-emulsion and the median droplet size of the emulsion particles is preferably from 0.39 xcexcm to 25 xcexcm.
WO-A1-00/71807 discloses a method of stabilising fabric softener compositions during high temperature storage. The examples show that by incorporating 3.5 to 15% by weight of a silicone emulsion into concentrated fabric conditioning compositions comprising 1,2-dihardened tallowoyloxyethyl, 3 tri-methyl ammoniopropane chloride (a quaternary ammonium material) high temperature storage stability is improved.
However, it has been found that a conditioning composition comprising a quaternary ammonium material based on triethanolamine, especially when the quaternary ammonium material contains saturated hydrocarbyl groups, can suffer from instability upon storage especially at high temperature when an emulsified silicone is present therein.
It is believed that this is due mainly to depletion flocculation.
xe2x80x9cDepletion flocculationxe2x80x9d was first recorded by Asakura and Oosawa in 1954 (J. Chem. Phys. 1954, 22, 1255) when they showed that the addition of a non-adsorbing polymer to a dispersion of colloidal particles led to an effective attractive interaction between themxe2x80x94flocculation.
Without wishing to be bound by theory, it is believed that quaternary ammonium materials based on triethanolamine are prone to depletion flocculation due to the presence of mono-ester linked quaternary ammonium species present in the continuous phase of the composition (i.e. mixed micelles). The introduction of an emulsified silicone exacerbates depletion flocculation by, firstly, liberating greater quantities of the mono-ester linked quaternary ammonium species into the continuous phase and, secondly, by the significant size difference between the particles present in the composition (i.e. between the smaller particles of the silicone emulsion and the larger liposomes of the quaternary ammonium material based on triethanolamine).
U.S. Pat. No. 5,336,419 discloses a nonionic emulsified silicone gel for ease of ironing and better looking garments. The softener dispersions range from 5.3 to 24wt % of a mixed softener system with 1 to 2.4wt % of a silicone emulsion.
WO 98/50502 discloses compositions comprising softening compounds based on triethanolamine and silicone emulsion mixtures.
The present invention seeks to address one or more of the above-mentioned problems, and, to give one or more of the above-mentioned benefits desired by consumers.
It has surprisingly been found that by incorporating a fatty component which comprises a long alkyl chain, such as fatty alcohols or fatty acids (hereinafter referred to as xe2x80x9cfatty complexing agentsxe2x80x9d) into softening compositions comprising a quaternary ammonium softening material having substantially fully saturated alkyl chains, at least some mono-ester component and at least some tri-ester component, and an emulsified silicone which comprises a nonionic emulsifier, wherein the fatty complexing agent is present in an amount significantly greater than normally present in traditional fabric softening compositions, then the stability and initial viscosity of the composition can be dramatically improved. In particular, undesirable thickening of the composition upon storage at high temperature can be avoided.
In the context of the present invention, xe2x80x9chigh temperature storagexe2x80x9d denotes storage at 37xc2x0 C. or above.
According to the present invention there is provided a fabric conditioning composition comprising:
(a) from about 7.5 to 80% by weight of an ester-linked quaternary ammonium fabric softening material comprising comprising at least one mono-ester linked component and at least one tri-ester linked component;
(b) 0.9% to 15% by weight of a fatty complexing agent;
(c) an emulsified silicone
wherein the weight ratio of the mono-ester linked component of compound (a) to compound (c) is from 5:1 to 1:5 and the emulsifier for the silicone comprises a nonionic emulsifier.
There is also provided a method for treatment of fabrics comprising contacting the above-mentioned composition with fabrics in a laundry treatment process.
In the context of the present invention, the term xe2x80x9ccomprisingxe2x80x9d means xe2x80x9cincludingxe2x80x9d or xe2x80x9cconsisting ofxe2x80x9d. That is the steps, components, ingredients, or features to which the term xe2x80x9ccomprisingxe2x80x9d refers are not exhaustive.
For the avoidance of doubt, the term xe2x80x9cemulsified siliconexe2x80x9d means that the silicone is emulsified prior to incorporation into the fabric conditioning composition but does not necessarily remain emulsified once incorporated therein.